B.Bagautdinov
(2014).
The structures of the CutA1 proteins from Thermus thermophilus and Pyrococcus horikoshii: characterization of metal-binding sites and metal-induced assembly.
Acta Crystallogr F Struct Biol Commun,
70,
404-413.
PubMed id: 24699729
DOI: 10.1107/S2053230X14003422
The structures of the CutA1 proteins from Thermus thermophilus and Pyrococcus horikoshii: characterization of metal-binding sites and metal-induced assembly.
B.Bagautdinov.
ABSTRACT
CutA1 (copper tolerance A1) is a widespread cytoplasmic protein found in
archaea, bacteria, plants and animals, including humans. In Escherichia coli it
is implicated in divalent metal tolerance, while the mammalian CutA1 homologue
has been proposed to mediate brain enzyme acetylcholinesterase activity and
copper homeostasis. The X-ray structures of CutA1 from the thermophilic
bacterium Thermus thermophilus (TtCutA1) with and without bound Na(+) at 1.7 and
1.9 Å resolution, respectively, and from the hyperthermophilic archaeon
Pyrococcus horikoshii (PhCutA1) in complex with Na(+) at 1.8 Å resolution
have been determined. Both are short and rigid proteins of about 12 kDa that
form intertwined compact trimers in the crystal and solution. The main
difference in the structures is a wide-type β-bulge on top of the TtCutA1
trimer. It affords a mechanism for lodging a single-residue insertion in the
middle of β2 while preserving the interprotomer main-chain hydrogen-bonding
network. The liganded forms of the proteins provide new structural information
about the metal-binding sites and CutA1 assembly. The Na(+)-TtCutA1 structure
unveils a dodecameric assembly with metal ions in the trimer-trimer interfaces
and the lateral clefts of the trimer. For Na(+)-PhCutA1, the metal ion
associated with six waters in an octahedral geometry. The structures suggest
that CutA1 may contribute to regulating intracellular metal homeostasis through
various binding modes.